private static void FindMaxIndexKernel(
ArrayView <Point> input,
int side,
Point a,
Point b,
ArrayView <DataBlock <int, float> > output)
{
var stride = GridExtensions.GridStrideLoopStride;
var index = -1;
var distance = 0f;
for (var i = Grid.GlobalIndex.X; i < input.Length; i += stride)
{
FindMaxIndex(a, b, input[i], side, i, ref index, ref distance);
}
var maxGroupDistance = GroupExtensions.Reduce <float, MaxFloat>(distance);
if (!distance.Equals(maxGroupDistance))
{
index = -1;
}
var maxGroupIndex = GroupExtensions.Reduce <int, MaxInt32>(index);
if (Group.IsFirstThread)
{
output[Grid.IdxX] = new DataBlock <int, float>(maxGroupIndex, maxGroupDistance);
}
}
public static void ChannelMinMaxKernel(
int channelIdx,
int numChannels,
ArrayView <float> input,
ArrayView <float> output)
{
MinFloat minReduction = default;
MaxFloat maxReduction = default;
// Each kernel will apply the reductions locally.
var stride = GridExtensions.GridStrideLoopStride;
var minReduced = minReduction.Identity;
var maxReduced = maxReduction.Identity;
for (var idx = Grid.GlobalIndex.X; idx < input.Length; idx += stride)
{
if (idx % numChannels == channelIdx)
{
minReduced = minReduction.Apply(minReduced, input[idx]);
maxReduced = maxReduction.Apply(maxReduced, input[idx]);
}
}
// Perform a block-wide reduction.
minReduced = GroupExtensions.Reduce <float, MinFloat>(minReduced);
maxReduced = GroupExtensions.Reduce <float, MaxFloat>(maxReduced);
// The first thread of the group is responsible for writing the
// reduced results.
if (Group.IsFirstThread)
{
minReduction.AtomicApply(ref output[0], minReduced);
maxReduction.AtomicApply(ref output[1], maxReduced);
}
}